Display screen or portion thereof with a graphical user interface



FIG. 1 a front view of a display screen or portion thereof with a graphical user interface showing our new design; and,

FIG. 2 is another front view of the display screen or portion thereof with a graphical user interface illustrating an example of as applied to a mobile terminal.

The broken line showing of a display screen or portions thereof represent the article of manufacture and forms no part of the claimed design. The broken line showing of symbols and numbers in the figures represent portions of the graphical user interface which form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with a graphical user interface, as shown and described. 